Competition between σ70and σ38in overlapping promoter regions. (a) Recruitment of RNA polymerase (RNAP) core enzyme to promoters upstream of 1,139 σ38-specific genes was recovered when rpoS was knocked out. RNAP binding intensity on the y-axis was the chromatin immunoprecipitation and microarray (ChIP-chip), intensity; the three red lines represent the first, second, and third quantiles. (b) Comparison of transcriptional expression of genes in wild type (WT) and ΔrpoS strains. Of 1,139 genes with σ38-specific promoters,178 had up-regulated transcription (red background) and 291 had down-regulated transcription (blue background). (c) Expression level of σ70 and σ38 was measured at both th transcriptional and translational levels. The amount of σ70 was abundant in exponential and stationary phase, and so it was absent in rpoS. (d) After rpoS knock-out, up-regulated genes were more strongly bound by σ70 than down-regulated genes.